Some musical instruments are played with a technique that produces a periodic change in frequency called vibrato. The vibrato characteristic is controlled by the player of the musical instrument and thus can be made more subtle or exaggerated at will. Very often it is desired that the vibrato effect occur only during sustained notes and not during rapid note sequences. For effect, the musician may choose to play a sustained note initially without vibrato and then gradually bring in the vibrato effect with increasing depth. This effect is called delayed vibrato. Further, some musical instruments exhibit frequency modulation of varying degrees at the onset of an audible tone with a diminishing effect as time passes. This modulation effect can be subtle, as a slight dip in frequency, or exaggerated, as several vibrato cycles. Such an effect may be called decayed vibrato. The combined effects of delayed vibrato and decayed vibrato, as they apply to electronic musical instruments, is the subject of this invention.
The two effects described above, delayed and decayed vibrato, have been implemented to varying degrees in digital electronic musical instruments in the past. However, the time variant parameters of these effects have not been responsive on an individually selective basis. That is to say, on an electronic musical instrument having a keyboard, these effects were not responsive on an individual key basis. If one key was held down while other keys were being played, either the latter notes would cause the resulting audible tone from a prior sustained note to be affected or the latter notes would not exhibit the desired dynamic modulation effect. In contrast, the present invention discloses a dynamic modulation controlled exhibiting independent response to each new key depression.
Some of the reasons for the creation of these dynamic modulation effects may be from among the following. Delayed vibrato has been used on certain electronic musical instruments for creating the effect of a stringed-instrument sound in a more accurate manner. The vibrato effect causes changes in the pitch of the resulting audible tone which is detected by the listener as an alternate sharping and flatting of the tone. Thus, the addition of a vibrato effect to a rapidly keyed sequence of notes has a certain detuning effect as heard by the listener. If the musician desires to rapidly key the electronic musical instrument to reproduce a desired sound, the delayed vibrato effect permits the electronic musical instrument to reproduce such sounds corresponding to depressed keys without the instantaneous detuning effects of non delayed vibrato. Without such delay a listener could detect an instantaneous detuning of the reproduced tones from a rapid keying sequence with the non delayed vibrato enabled.
The second dynamic modulation effect is decayed vibrato. This is an effect which would in general not be completely controlled by the player but would be an inherent characteristic of an instrument. An example of such a natural effect can be observed when a stringed instrument is plucked. When decayed vibrato is selected, it causes an immediate frequency modulation followed by a decay of the modulation to a sustained tone. Thus, a realism in reproducing percussive effects by an electronic musical instrument is achieved. Both the delayed and decayed vibrato effects may be manually set to control both the depth and rate of change of the effects. These manually controlled characteristics will be discussed more fully hereinafter. It should be noted that neither the delayed nor the decayed vibrato has any tonal dependence among the depressed keys. For any given keying sequence these modulation effects are entirely independent of the keys depressed prior to the enabling of the effect and those depressed subsequently.
Accordingly, it is an object of this invention to provide both delayed and decayed vibrato in an electronic musical instrument where the time variant parameters of such effects are responsive to individually depressed keys.
A further object of the present invention is to provide for the control of the depth of each of the two effects, delayed and decayed vibrato. The depth of each effect being the degree to which the frequency of the reproduced tone deviates from its nominal pitch.
Another object of the present invention is to provide for the control of the rate of change or deviation of the time period of each of the effects, delayed and decayed vibrato.
Other objects will appear hereinafter.